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authorWei Wang <weiwan@google.com>2019-05-16 23:30:54 +0300
committerDavid S. Miller <davem@davemloft.net>2019-05-17 00:30:53 +0300
commit510e2ceda031eed97a7a0f9aad65d271a58b460d (patch)
treebd45f013d94d901034ec055e63cf83fd8427e89f /net
parent9a6c8bf91b6025b1bb95d4fb454a16019ad22fc4 (diff)
downloadlinux-510e2ceda031eed97a7a0f9aad65d271a58b460d.tar.xz
ipv6: fix src addr routing with the exception table
When inserting route cache into the exception table, the key is generated with both src_addr and dest_addr with src addr routing. However, current logic always assumes the src_addr used to generate the key is a /128 host address. This is not true in the following scenarios: 1. When the route is a gateway route or does not have next hop. (rt6_is_gw_or_nonexthop() == false) 2. When calling ip6_rt_cache_alloc(), saddr is passed in as NULL. This means, when looking for a route cache in the exception table, we have to do the lookup twice: first time with the passed in /128 host address, second time with the src_addr stored in fib6_info. This solves the pmtu discovery issue reported by Mikael Magnusson where a route cache with a lower mtu info is created for a gateway route with src addr. However, the lookup code is not able to find this route cache. Fixes: 2b760fcf5cfb ("ipv6: hook up exception table to store dst cache") Reported-by: Mikael Magnusson <mikael.kernel@lists.m7n.se> Bisected-by: David Ahern <dsahern@gmail.com> Signed-off-by: Wei Wang <weiwan@google.com> Cc: Martin Lau <kafai@fb.com> Cc: Eric Dumazet <edumazet@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/route.c51
1 files changed, 27 insertions, 24 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 27c0cc5d9d30..7a014ca877ed 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -111,8 +111,8 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
int iif, int type, u32 portid, u32 seq,
unsigned int flags);
static struct rt6_info *rt6_find_cached_rt(const struct fib6_result *res,
- struct in6_addr *daddr,
- struct in6_addr *saddr);
+ const struct in6_addr *daddr,
+ const struct in6_addr *saddr);
#ifdef CONFIG_IPV6_ROUTE_INFO
static struct fib6_info *rt6_add_route_info(struct net *net,
@@ -1573,31 +1573,44 @@ out:
* Caller has to hold rcu_read_lock()
*/
static struct rt6_info *rt6_find_cached_rt(const struct fib6_result *res,
- struct in6_addr *daddr,
- struct in6_addr *saddr)
+ const struct in6_addr *daddr,
+ const struct in6_addr *saddr)
{
+ const struct in6_addr *src_key = NULL;
struct rt6_exception_bucket *bucket;
- struct in6_addr *src_key = NULL;
struct rt6_exception *rt6_ex;
struct rt6_info *ret = NULL;
- bucket = rcu_dereference(res->f6i->rt6i_exception_bucket);
-
#ifdef CONFIG_IPV6_SUBTREES
/* fib6i_src.plen != 0 indicates f6i is in subtree
* and exception table is indexed by a hash of
* both fib6_dst and fib6_src.
- * Otherwise, the exception table is indexed by
- * a hash of only fib6_dst.
+ * However, the src addr used to create the hash
+ * might not be exactly the passed in saddr which
+ * is a /128 addr from the flow.
+ * So we need to use f6i->fib6_src to redo lookup
+ * if the passed in saddr does not find anything.
+ * (See the logic in ip6_rt_cache_alloc() on how
+ * rt->rt6i_src is updated.)
*/
if (res->f6i->fib6_src.plen)
src_key = saddr;
+find_ex:
#endif
+ bucket = rcu_dereference(res->f6i->rt6i_exception_bucket);
rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
ret = rt6_ex->rt6i;
+#ifdef CONFIG_IPV6_SUBTREES
+ /* Use fib6_src as src_key and redo lookup */
+ if (!ret && src_key && src_key != &res->f6i->fib6_src.addr) {
+ src_key = &res->f6i->fib6_src.addr;
+ goto find_ex;
+ }
+#endif
+
return ret;
}
@@ -2672,12 +2685,10 @@ u32 ip6_mtu_from_fib6(const struct fib6_result *res,
const struct in6_addr *daddr,
const struct in6_addr *saddr)
{
- struct rt6_exception_bucket *bucket;
const struct fib6_nh *nh = res->nh;
struct fib6_info *f6i = res->f6i;
- const struct in6_addr *src_key;
- struct rt6_exception *rt6_ex;
struct inet6_dev *idev;
+ struct rt6_info *rt;
u32 mtu = 0;
if (unlikely(fib6_metric_locked(f6i, RTAX_MTU))) {
@@ -2686,18 +2697,10 @@ u32 ip6_mtu_from_fib6(const struct fib6_result *res,
goto out;
}
- src_key = NULL;
-#ifdef CONFIG_IPV6_SUBTREES
- if (f6i->fib6_src.plen)
- src_key = saddr;
-#endif
-
- bucket = rcu_dereference(f6i->rt6i_exception_bucket);
- rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
- if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
- mtu = dst_metric_raw(&rt6_ex->rt6i->dst, RTAX_MTU);
-
- if (likely(!mtu)) {
+ rt = rt6_find_cached_rt(res, daddr, saddr);
+ if (unlikely(rt)) {
+ mtu = dst_metric_raw(&rt->dst, RTAX_MTU);
+ } else {
struct net_device *dev = nh->fib_nh_dev;
mtu = IPV6_MIN_MTU;